Effects of insulin-like growth factor (IGF) binding proteins (BPs) -3 and -6 on DNA synthesis of rat osteoblasts: further evidence for a role of auto-/paracrine IGF I but not IGF II in stimulating osteoblast growth

Biochem Biophys Res Commun. 1995 Jul 6;212(1):242-8. doi: 10.1006/bbrc.1995.1962.

Abstract

IGFBP-3 and IGFBP-6 were used to study whether both IGF I and IGF II play a role in auto-/paracrine stimulation of rat osteoblast growth. Both IGFBPs decreased basal DNA synthesis in neonatal rat calvaria cells but with different potencies. Consistent with their IGF binding affinities, IGFBP-3 blocked both IGF I- and IGF II-stimulated DNA synthesis, whereas IGFBP-6 preferentially blocked IGF II-stimulated DNA synthesis. These inhibitory effects of the two IGFBPs can be fully explained by the sequestration of IGFs. Because IGFBP-6 preferentially binds IGF II and is much less potent than IGFBP-3 in decreasing basal DNA synthesis in calvaria cells, IGF I but not IGF II appears to be an important auto-/paracrine stimulator of DNA synthesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Animals, Newborn
  • Carrier Proteins / metabolism
  • Carrier Proteins / pharmacology*
  • Cell Line
  • DNA / biosynthesis*
  • DNA / drug effects
  • Humans
  • Insulin-Like Growth Factor Binding Protein 6
  • Insulin-Like Growth Factor Binding Proteins
  • Insulin-Like Growth Factor I / analogs & derivatives
  • Insulin-Like Growth Factor I / metabolism*
  • Insulin-Like Growth Factor I / pharmacology
  • Insulin-Like Growth Factor II / metabolism*
  • Kinetics
  • Osteoblasts / cytology
  • Osteoblasts / drug effects
  • Osteoblasts / metabolism*
  • Rats
  • Recombinant Proteins / metabolism
  • Skull
  • Thymidine / metabolism

Substances

  • Carrier Proteins
  • Insulin-Like Growth Factor Binding Protein 6
  • Insulin-Like Growth Factor Binding Proteins
  • Recombinant Proteins
  • insulin-like growth factor I, Gln(3)-Ala(4)-Tyr(15)-Leu(16)-
  • Insulin-Like Growth Factor I
  • Insulin-Like Growth Factor II
  • DNA
  • Thymidine